Recent epidemiological observations have revealed that dietary whole grains are inversely related to fasting insulin and confer protection from diabetes, coronary heart disease, and cancer independent of body weight and other dietary behaviors and lifestyle habits. Therefore, the purpose of this study is to collect pilot data to examine the effects of whole grains on insulin sensitivity and risk factors for cardiovascular disease and cancer. This randomized cross-over design includes 6 weeks of a whole grain diet, 6 to 9 weeks of a usual diet washout, and 6 weeks of a refined grain diet in middle-aged overweight adults without diabetes.